Pneumatic tire



April 29, 194i. B. H. BENsoN Erm.

PNEUMATIG TIRE Filed March 1, 1939 Sheets-Sheet 1 y l lnvenors. Benjamin l-LBenson Anys'.

April 29, 1941.

B. H. BENSON El' AL PNEUMATIC TIRE Filed March 1, i939' 2 sheets-sheet 2 Fgl.

lnven'rorvs. Benjamn H. Benson Bernard E. Mendelsohn by/ewcwm ATTys.

y Patented pr. 29, 1941 PN EU'MATIC TIRE rsenjamin Howard Benson and Bernard E. Mendelsohn, Brookline, Mass.

Application March 1, 1939, serial o. 259,180

' A1 Claim.

rI'his invention relates to inner tubes for pneumatic tires, and particularly to inner tubes of the twin-tube type which are constructed to providev a constantly open leak port or passage between the two tube sections so that in case one of the tube sections becomes deated by a puncture or a blowout, there will be a delayed deiiation' of the other tubeV section, thus giving the driver of the automobile time to bring it to rest before complete deflation takes place.

Gne of the objects of our present invention is to provide a novel construction by which the constantly open leak port, which constitutes a constantly open communication between the tube sections, is formed by registering naked leak holes in the contacting walls of the two tube sections, said leak holes being held in registering relation by the cementing together of the mating walls of the tube sections circumiacent said holes.r Another object of the invention is to provide a novel construction which facilitates the registration of the naked leak holes when the tube sections are being assembled in their twin-tube relation. Y

In accordance with the present invention, this constantly open leak passageis formed directly in the contacting walls of the tube sections and without the use of nipples, buttons or other. similar adjuncts which necessarily increase the cost of manufacture of the tire.

In the drawings wherein we have illustrated A' some selected embodiments of our invention;

Fig. 1 is a sectional view through an inner tube made in accordance with our invention, the tube casing being shown in dotted lines;

Figs. 2 and 3 are fragmentary sectional perspective views illustrating the portions of the two tube sections which have the leak holes therein;

Fig. 4 is a view similar to Fig. 1 showing a different embodiment of the invention;

Fig. 5 is a fragmentary sectional view showing a portion of one of the tube sections;

Fig. 6 is a face view of Fig. 5;

Fig. 'l is a section on the line 'l--|, Fig. 6.

In the drawings, the twin tube sections of the inner tire are indicated at l and 2 respectively. These two tube sections combined constitute the inner tube of the tire and are shown located within a tire casing 3 which is mounted on a rim 4 as usual in pneumatic tires, the tire casing and the rim being shown in dotted lines.

The two tube sections l and 2 may be initially made to have any desired cross-sectional shape, but we will preferably makeA these tube sections with a D-shape in cross-section, each tube seotion having a dat wall portion 5 and a rounded wall portion 6. `When the tube sections are/assembled within the casing 3, the iiat wall portions 5 thereof are in mating contacting relation. The complete inner tube will thus be formed with two air chambers 'I and 8, each of which extends clear around the tire.

The two tube sections l and 2 are made separately and are then assembled to form the inner tube of the tire.

As stated above, the invention relates tov that known type of twin-tube inner tube which is formed with a. constantly open communication between the two air chambers 1 and 8.

In accordance with the present invention, this constantly open leak passage is formed byv providing the walls 5 of each of the tube sections l andZ with a naked leak hole which registers with Vthat formed in the other wall 5.

The. wall 5 of the tube section I is shown as having a small leak hole 9 extending therethrough,.such leak hole being formed directly in the rubber of the wall 5. The wall 5 of the tube section` 2 also has a registering leak hole I0 formed directly in the rubber of the wall, said leak hole l0 registering with the leakhole 9.

In order to hold the registering leak holes 9 and I 0 in registering relation, we propose to cement or unite together the contacting faces of the mating walls 5 in a zone circumjacent the leakholes 9 and I0. In Fig. 3 the stippled portion of the outer face of the wall 5 of the tube section 2 represents the portion of said wall which is cemented or otherwise united to the wall 5 of the tube section I. These tube sections may be united in this zone immediately surrounding the leak holes by applying a suitable cement to the portion of the outer face of each wall 5 immediately circuma'acent the leak hole so that when the two tube sections are assembled with each other with the leak holes in registering relation, said tube sections will become cemented or otherwise united throughout this zone.

In the preferred embodiment ofthe invention the leak hole in one of; the tube sections is made larger than that of the other tube section so as to make it easier to maintain the registering relation of the leak holes while the two portions of the two walls 5 circumjacent the holes are being cemented together. In the construction shown in Fig. 1, the hole I0 in the wall 5 ofthe tube section 2 is made larger than the leak hole 9 in the tube section l. With this construction, the eiective size of the leak passage is determined by the size of the smaller leak hole 9. The use of the larger leak hole in one of the walls 5 permits some latitude in the relative position of the Walls 5 as the portions cincumjacent the leak holes are being cemented together without destroying the registering relation between the leak holes. If the leak hole in the Wall 5 of the tube section 2 were only as large as the leak hole 9 in the section I, it would be difficult to assemble the two tube sections in their mating relation and with the small leak holes in exact registry, but this operation of cementing the two walls 5 together with the leak holes 9 and Il) registering with each other is greatly faci-litated by having the leak hole I0 larger than the leak hole 9.

One of the tube sections, preferably the tube section I having the smaller leak hole 9, is provided with the usual inating valve indicated at I I by which the inner tube is inflated. Since the two chambers 1 and 8 have a constantly open communication through the registering leak holes S and Ill, the tube can be inflated through the' ination valve II, because the air which is introduced into the chamber I will leak through the leak port into the chamber 8 and ultimately the pressure in-both chambers will be equalized so that the two walls 5 will Vassume a central portion within the tire.

If either chamber 'I or 8 becomes suddenly deiiated by a blowout or a puncture, the air within the other chamber will suffice to hold up the tire and although there will be a slow leakage of air from the undamaged tube section into the other, yet the restricted leak opening will delay complete deflation of the other tube sectionv until the driver of the 'car has had ample time to bring the car to rest.

In the construction illustrated in Fig. 1, the wall 5 of the tube section I is provided with suitable reinforcement I2 at the point where the small hole 9 is located and this reinforcement serves to maintain the constantly open condition of said small leak hole and also to obviate danger that the wall 5 will become torn at the small leak hole during inating or deflating of the tire. This reinforcement also prevents the small leak hole from expanding as the inner tube stretches, or from closing up to an extent to prevent proper functioning.

In Fig. 4, we have shown a construction wherein the two tube sections are indicated at Ia and 2a, and the tube section Ia is provided with a member being cemented or vulcanized to the wall 5a.

The other tube section 2a is provided in its wall 5a with an opening I6 of a size to receive the reinforcement I5 so that when the two tube sections are in assembled relation, the reinforcement I5 fills the opening I6 of the tube section 2a. This reinforcement I5 has a small opening I'I therein which registers with the small leak port 9a.

I'hese tube sections Ia and 2a, are held in their assembled relation by having at least the portion of the contacting walls of the two tube sections surrounding the leak port cemented together.

The reinforcement I5 serves to prevent the small leak port 9a from closing up and also serves to maintain its small or restricted diameter even when the tube section la is stretched. When the two tube sections Ia, 2a are assembled, as shown in Fig. 4, the reinforcement I5, which is permanently secured to the exterior of the wall 5a of the tube section Ia, becomes, in effect, part of the wall of the compartment 8a.

Although the leak port I1 through the reinforcement I5 is relatively small and of approximately the same size as the leak port 9a through the wall 5a, yet it is much easier to secure the relatively small reinforcement member I5 to the wall 5a with the leak ports 9a and I1 in exact register than it would to secure the wall 5a of the tube 2a with a leak hole therein as small as that shown at I'I to the wall 5a of the tube section I o, and to maintain the two small leak holes in alinement during such operation. The provision of the reinforcement member I 5, therefore, facilitates the securing together of the two tube sections and the maintenance of the leak holes in registry with each other during this operation.

We will preferably make the reinforcement I5 slightlyk thicker than the wall 5a of the tube section 2a sc that when the sections are assembled, th'e inner face I8 of the reinforcement projects slightly beyond the inner face of the wall 5a. This inner face I8 of the reinforcement I5 is shown as being provided with grooves I9 which radiate from the opening II. The purpose of these grooves is to prevent the closing of the leak port by the engagement of the wall 5a of the tube section 2a with the outer Wall of said section when the latter is deflated by a puncture or a blowout. If said section 2a is thus deflated, the two-ply partition comprising the two walls 5a will move over against one side of the tire, but since the reinforcement I5 is slightly thicker than the wall 5a, said grooved face I8 of the reinforcement will engage the side wall of the tire and the grooves I5 thus Will provide open passages through which the air in the undamaged tube section Ia can slowly escape.

In the construction shown in Eig. 4, the wall 5a of the tube section Ia is also shown as having an interior reinforcement I2a which is provided onfits exposed face with radial grooves which function similar to the grooves I9 if the tube section Ia is deflated.

We claim:

An inner tube for ya pneumatic tire comprising twin-tube sections having mating walls in contact with each other, the mating wall of one tube section having an unobstructed naked leak hole therethrough, and also having a reinforcement permanently secured to its exterior face surrounding the leak hole and provided with a continuation of said leak hole, the mating wall of the other tube section having an opening therethrough in which said reinforcement is received, said reinforcement being thicker than the last named mating wall and extending slightly beyondthe inner face thereof, the inner face of the reinforcement having radial grooves communieating with the leak hole, the contacting faces of said mating walls being cemented together in a zone immediately surrounding the leak hole.

BENJAMIN HOWARD BENSON. BERNARD E, MENDELSOHN. 

